mirror of
https://git.code.sf.net/p/libpng/code.git
synced 2025-07-10 18:04:09 +02:00
[master] Implement two-pass png_decompress_chunk() function
suggested by John Bowler. Does not waste memory, does only one malloc() to the measured decompressed size.
This commit is contained in:
Glenn Randers-Pehrson
parent
a69064328b
commit
877b08d6d2
@ -1,7 +1,7 @@
|
||||
|
||||
/* pngpriv.h - private declarations for use inside libpng
|
||||
*
|
||||
* libpng version 1.4.1beta05 - January 26, 2010
|
||||
* libpng version 1.4.1beta06 - January 28, 2010
|
||||
* For conditions of distribution and use, see copyright notice in png.h
|
||||
* Copyright (c) 1998-2010 Glenn Randers-Pehrson
|
||||
* (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
|
||||
@ -306,6 +306,8 @@ PNG_EXTERN void png_crc_read PNGARG((png_structp png_ptr, png_bytep buf,
|
||||
/* Decompress data in a chunk that uses compression */
|
||||
#if defined(PNG_zTXt_SUPPORTED) || defined(PNG_iTXt_SUPPORTED) || \
|
||||
defined(PNG_iCCP_SUPPORTED) || defined(PNG_sPLT_SUPPORTED)
|
||||
PNG_EXTERN png_size_t png_measure_decompressed_chunk PNGARG((png_structp
|
||||
png_ptr, int comp_type, png_size_t chunklength, png_size_t prefix_length));
|
||||
PNG_EXTERN void png_decompress_chunk PNGARG((png_structp png_ptr,
|
||||
int comp_type, png_size_t chunklength, png_size_t prefix_length,
|
||||
png_size_t *data_length));
|
||||
|
||||
154
pngrutil.c
154
pngrutil.c
@ -1,7 +1,7 @@
|
||||
|
||||
/* pngrutil.c - utilities to read a PNG file
|
||||
*
|
||||
* Last changed in libpng 1.4.1 [January 26, 2010]
|
||||
* Last changed in libpng 1.4.1 [January 28, 2010]
|
||||
* Copyright (c) 1998-2010 Glenn Randers-Pehrson
|
||||
* (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
|
||||
* (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
|
||||
@ -201,6 +201,68 @@ png_crc_error(png_structp png_ptr)
|
||||
|
||||
#if defined(PNG_READ_zTXt_SUPPORTED) || defined(PNG_READ_iTXt_SUPPORTED) || \
|
||||
defined(PNG_READ_iCCP_SUPPORTED)
|
||||
png_size_t
|
||||
png_measure_decompressed_chunk(png_structp png_ptr, int comp_type,
|
||||
png_size_t chunklength, png_size_t prefix_size)
|
||||
{
|
||||
png_charp text;
|
||||
png_charp test = "X";
|
||||
png_size_t text_size = 0;
|
||||
|
||||
if (comp_type == PNG_COMPRESSION_TYPE_BASE)
|
||||
{
|
||||
int ret = Z_OK;
|
||||
|
||||
png_ptr->zstream.next_in = (png_bytep)(png_ptr->chunkdata + prefix_size);
|
||||
png_ptr->zstream.avail_in = (uInt)(chunklength - prefix_size);
|
||||
png_ptr->zstream.next_out = png_ptr->zbuf;
|
||||
png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
|
||||
|
||||
text = NULL;
|
||||
|
||||
while (png_ptr->zstream.avail_in)
|
||||
{
|
||||
ret = inflate(&png_ptr->zstream, Z_PARTIAL_FLUSH);
|
||||
if (ret != Z_OK && ret != Z_STREAM_END)
|
||||
{
|
||||
inflateReset(&png_ptr->zstream);
|
||||
png_ptr->zstream.avail_in = 0;
|
||||
break;
|
||||
}
|
||||
if (!png_ptr->zstream.avail_out || ret == Z_STREAM_END)
|
||||
{
|
||||
if (text == NULL) /* Initialize the decompression buffer */
|
||||
{
|
||||
text_size = prefix_size +
|
||||
png_ptr->zbuf_size - png_ptr->zstream.avail_out;
|
||||
|
||||
text=test;
|
||||
}
|
||||
else /* Enlarge the decompression buffer */
|
||||
{
|
||||
text_size += png_ptr->zbuf_size - png_ptr->zstream.avail_out;
|
||||
#ifdef PNG_CHUNK_MALLOC_LIMIT_SUPPORTED
|
||||
if (text_size >= png_ptr->user_chunk_malloc_max - 1)
|
||||
return 0;
|
||||
#endif
|
||||
}
|
||||
}
|
||||
if (ret == Z_STREAM_END)
|
||||
break;
|
||||
|
||||
else
|
||||
{
|
||||
png_ptr->zstream.next_out = png_ptr->zbuf;
|
||||
png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
|
||||
}
|
||||
}
|
||||
|
||||
inflateReset(&png_ptr->zstream);
|
||||
png_ptr->zstream.avail_in = 0;
|
||||
}
|
||||
return text_size;
|
||||
}
|
||||
|
||||
/*
|
||||
* Decompress trailing data in a chunk. The assumption is that chunkdata
|
||||
* points at an allocated area holding the contents of a chunk with a
|
||||
@ -216,6 +278,15 @@ png_decompress_chunk(png_structp png_ptr, int comp_type,
|
||||
static PNG_CONST char msg[] = "Error decoding compressed chunk";
|
||||
png_charp text;
|
||||
png_size_t text_size;
|
||||
png_size_t expanded_size;
|
||||
|
||||
expanded_size= png_measure_decompressed_chunk(png_ptr, comp_type,
|
||||
chunklength, prefix_size);
|
||||
if (expanded_size == 0)
|
||||
{
|
||||
*newlength=0;
|
||||
return;
|
||||
}
|
||||
|
||||
if (comp_type == PNG_COMPRESSION_TYPE_BASE)
|
||||
{
|
||||
@ -274,8 +345,7 @@ png_decompress_chunk(png_structp png_ptr, int comp_type,
|
||||
{
|
||||
if (text == NULL) /* Initialize the decompression buffer */
|
||||
{
|
||||
text_size = prefix_size +
|
||||
png_ptr->zbuf_size - png_ptr->zstream.avail_out;
|
||||
text_size = expanded_size;
|
||||
|
||||
text = (png_charp)png_malloc_warn(png_ptr, text_size + 1);
|
||||
if (text == NULL)
|
||||
@ -291,64 +361,6 @@ png_decompress_chunk(png_structp png_ptr, int comp_type,
|
||||
*(text + text_size) = 0x00;
|
||||
buffer_size = text_size;
|
||||
}
|
||||
else /* Enlarge the decompression buffer */
|
||||
{
|
||||
png_charp tmp = text;
|
||||
png_size_t new_text_size;
|
||||
|
||||
new_text_size = text_size + png_ptr->zbuf_size -
|
||||
png_ptr->zstream.avail_out;
|
||||
|
||||
if (new_text_size > buffer_size)
|
||||
{
|
||||
if (png_ptr->zstream.avail_out)
|
||||
buffer_size = new_text_size;
|
||||
else
|
||||
buffer_size += buffer_size;
|
||||
|
||||
#ifdef PNG_CHUNK_MALLOC_LIMIT_SUPPORTED
|
||||
if (buffer_size >= png_ptr->user_chunk_malloc_max - 1)
|
||||
{
|
||||
if (new_text_size >=
|
||||
png_ptr->user_chunk_malloc_max - 1)
|
||||
{
|
||||
png_free(png_ptr, tmp);
|
||||
png_warning(png_ptr,
|
||||
"No space for decompressed chunk");
|
||||
text = NULL;
|
||||
}
|
||||
else
|
||||
{
|
||||
buffer_size = png_ptr->user_chunk_malloc_max - 1;
|
||||
text = (png_charp)png_malloc_warn(png_ptr,
|
||||
buffer_size + 1);
|
||||
}
|
||||
}
|
||||
|
||||
else
|
||||
text = (png_charp)png_malloc_warn(png_ptr,
|
||||
buffer_size + 1);
|
||||
#else
|
||||
text = (png_charp)png_malloc_warn(png_ptr,
|
||||
buffer_size + 1);
|
||||
#endif
|
||||
|
||||
if (text == NULL)
|
||||
{
|
||||
png_warning(png_ptr,
|
||||
"Not enough memory to decompress chunk");
|
||||
break;
|
||||
}
|
||||
|
||||
png_memcpy(text, tmp, text_size);
|
||||
png_free(png_ptr, tmp);
|
||||
}
|
||||
/* FIX ME: zTXt chunk written by pngtest is 6 bytes too large */
|
||||
png_memcpy(text + text_size, png_ptr->zbuf,
|
||||
(png_ptr->zbuf_size - png_ptr->zstream.avail_out));
|
||||
text_size += png_ptr->zbuf_size - png_ptr->zstream.avail_out;
|
||||
*(text + text_size) = 0x00;
|
||||
}
|
||||
}
|
||||
if (ret == Z_STREAM_END)
|
||||
break;
|
||||
@ -360,26 +372,6 @@ png_decompress_chunk(png_structp png_ptr, int comp_type,
|
||||
}
|
||||
}
|
||||
|
||||
if (text != NULL && buffer_size > text_size)
|
||||
{
|
||||
/* Reduce text allocation to actual size */
|
||||
png_charp tmp;
|
||||
|
||||
tmp = text;
|
||||
text = (png_charp)png_malloc_warn(png_ptr,
|
||||
text_size);
|
||||
|
||||
if (text == NULL)
|
||||
text = tmp;
|
||||
|
||||
else
|
||||
{
|
||||
png_memcpy(text, tmp, text_size + 1);
|
||||
png_free(png_ptr, tmp);
|
||||
}
|
||||
|
||||
}
|
||||
|
||||
if (ret != Z_STREAM_END)
|
||||
{
|
||||
#ifdef PNG_STDIO_SUPPORTED
|
||||
|
||||
Loading…
x
Reference in New Issue
Block a user